1. Field of the Invention
This invention relates to two-component zoom objectives suitable for use in photographic devices of the lens shutter type or the like.
2. Description of the Prior Art
In photographic objectives for still cameras a wide acceptance has been found by zoom lenses having a range on the order of 1.5 to 2.0. Most of these zoom lenses are comprised of two components of negative and positive powers counting from the front and are so-called short zooms. Of these short zooms there are known, for example, Japanese Laid Open Patents Nos. Sho 53-91756, Sho 52-153752, Sho 52-152250, Sho 52-26236, Sho 49-29146, Sho 53-60656 and Sho 53-60246. Further, as an advanced form of this type zoom lens, it is proposed that the rear component of positive power is divided into two parts which are made movable independently of each other for the zooming purpose with an advantage that the zooming range is extended, or the bulk and size of the lens system is minimized, as, for example, in Japanese Laid Open Patent Application Nos. Sho 54-26754, Sho 53-103753 and Sho 53-34539 and U.S. Pat. No. 3,771,853.
The above-described types of zoom lenses has so long a back focus as to be generally used with a single lens reflex camera that is equipped with a mirror constituting part of a finder system in a space between the rear vertex of the lens and the film plane. Therefore, when this type zoom lens is attached to a lens shutter camera which does not necessitate the arrangement of any particular optical element in the space between the lens and the film plane, because of its having such long back focus as has been mentioned above, though the lens system itself is of not so much large size, it is unavoidable to result in the camera of large bulk and size as a whole.